1. Field of the Invention
The present invention relates generally to sensor-based systems, and more particularly to a multi-sensor collision avoidance system which combines data from two or more sensors to provide range, range rate, or location information.
2. Background Information
The roads are becoming more and more congested with vehicular traffic. As traffic congestion has increased, the number of accidents has also increased. Some of these accidents can be traced to driver inattentiveness or to the failure of the driver to see another vehicle. What is needed is a system and method for warning drivers of possible problems before the problems result in an accident.
Systems for making drivers aware of objects external to their vehicle have been around for a long time. Mirrors, and sometimes combinations of mirrors, are being used to reveal locations hidden to the driver's view (i.e. "blind spots"). Mirrors, however, have a deficiency in that the driver can only look in one spot at any one time. If they look behind the vehicle, see that the way is clear, start looking elsewhere and then a vehicle pulls behind them, they won't see it and may back into the vehicle. There is a similar problem with changing lanes. Mirrors don't work well in changing lanes, particularly in tractor-trailer rigs, since, as soon as the rig begins to turn, the mirror that looked down along the side of the vehicle is directed into the side of the trailer and the driver is blinded to activity on that side of his truck.
More recently, trucking and bussing companies have used backup alarms to warn bystanders that the truck is backing. The problem with backup alarms is that if you have somebody with a hearing problem, or if you had an immovable object such as a car or a trash container, the alarm isn't going to move that object out of the way.
Companies have also experimented with the use of video systems to view blind spots. For example, garbage pickup trucks for Browning-Ferris are using video systems which have a video camera installed on the back of the truck and a monitor up in the cab. Some recreational vehicle (RV) owners are doing the same thing. The problem with the video system approach is that such systems are expensive (even if you use an inexpensive approach, it would likely cost into the $1,000-$1,500 price range) and video monitors mounted in the cab can distract the driver from what is happening outside his vehicle. Finally, video lenses do not give depth perception. So, when drivers are backing a vehicle, they don't know how close they are to an object they are trying to avoid.
A final approach taken by a number of companies is the use of sensors to locate objects external to the vehicle. Electronic Controls Company of Boise, Idaho sells an ultrasonic sensor system that assists drivers in determining all is clear before the driver changes lanes, backs up or docks. The system includes ultrasonic sensors mounted on the back and sides of the vehicle and an alert module mounted in the cab of the vehicle. Each ultrasonic sensor continuously monitors a defined detection zone for objects moving within the zone. When a vehicle enters the detection zone, the sensor measures the time between sending the sound wave and receiving its reflection and sends that measurement to the cab.
Sonar Safety Systems of Santa Fe Springs, Calif. has a rear-mounted sensor system which detects objects in three distance zones from the rear of the vehicle. That is, it doesn't display distance to the object. Instead, the system provides alarms and audible feedback that inform the driver whether the obstacle is real close (Zone III), out a little farther (Zone II), or even farther out yet (Zone I). And it only looks up to 8 feet behind the vehicle. They also have a single sensory unit where they only put one sensor in the back.
A common problem with rear-mounted sensors to date is that sensors mounted on the rear of the vehicle detect the distance from the sensor to the object, not the perpendicular distance from the vehicle to the object. In addition, these systems do not communicate to the driver the transverse location of the object (i.e., is the object directly behind the vehicle, off to the side, or far enough to the left or right that the driver will not hit it). Furthermore, range measurement often does not exist, or is inaccurate.
The collision avoidance systems used to date are deficient in other ways as well. For instance, the systems provide only partial coverage around the periphery of the vehicle. That is, they either lack a forward-looking detection capability, lack range and range rate measurement capability or they lack sufficient detection capability around the periphery of the vehicle to eliminate blind spots. Furthermore, even if present, range measurement often is inaccurate. Finally, those systems which do have forward-looking detection are prone to a high rate of false alarms from the environment or to distracting off-the-road clutter.
Systems to date do not provide an adequate solution for the combination tractor-trailer rig. Armatron International of Melrose, Massachusetts has a side and rear obstacle detection system which includes wireless communications between the tractor and trailer, however, the sensors are all hard-wired to the trailer. This does not address the need in which tractors often are required to pull a multitude of trailers, some of which are owned by different companies, which are not likely to be equipped with any sensors.
Finally, systems to date lack the programmability to address the configuration and installation variables that influence the integrity of the sensor data. In addition, current systems are designed such that changes in the transmitted sensor frequency require a redesign of the software algorithms.
What is needed is a collision avoidance system and method which avoids these deficiencies.